Used for shaping a radiused fretboard and leveling installed frets. The side of the grooves is comfortable to hold and has good smoothness, so you not have to worry about being hurt by tiny burrs.
Guitar Fretboard Radius Sanding Blocks (Various Length and Radius)
Guitar Neck Radius Sanding Block - Hellfire - The Sandman - Modular - 3 Lengths
Guitar Neck Radius Sanding Block - Hellfire - The Sandman
Guitar Radius Sanding Block Fret Leveling Fingerboard 9.5 Inch Guitar Tools
Wood Guitar Radius Sanding Block Fret Leveling Fingerboard 9.5 Inch Guitar Tools
Guitar Radius Sanding Block Fret Leveling Fingerboard 12 Inch Guitar Tools